基于宏细观统一本构模型的复合材料湿热应力分析

基于有限体积直接平均方法(Finite-volume direct averaging micromechanics,FVDAM),建立了一种从复合材料细观到宏观的统一本构模型。根据均匀化方法和连续介质力学构建复合材料的宏细观相关矩阵,通过该矩阵将细观组分材料的损伤性能传递到宏观复合材料中,计算了湿热环境中复合材料的细观应力场。结果表明:FVDAM采用子胞边界平均位移作为未知量,使本构模型中的未知量总数大为减小,相对提高了模型的效率,但这些方程都是建立在平均意义上的,因此预测的应力场存在一定的不连续性;湿热环境下,前期的吸湿有缓解热残余应力的作用,随着时间的增加,吸湿的影响逐渐超过热残余应力的影响。

Research on Hygrothermal Stresses of Composite Based on Unified Macro- and Micro-constitutive Model

Based on finite-volume direct averaging micromechanic s (FVDAM), which is a multi-scale finite element method for composite, a unifi e d macro- and micro-constitutive model for composite structures is developed. T he global stiffness matrix is constructed based on homogenization theory and co ntinuum medium mechanics, through which the meso-damage properties of fiber and matrix are transferred to macro-material. Hygrothermal stress fields are cal c ulated using the model. The results show that the efficiency of the FVDAM model is promoted for the reason of taking the surface-averaged fluctuating displac e ments as basic unknown micro-variables, and the total number of unknowns is d ecre a sed a lot. Because the equations are built on the basis of averaged meaning, th ere are discontinuities in the solved stress fields. The initial moisture conten t can reduce the thermal residual stress, but the hygroscopic stress would e xc eed thermal residual stress finally.